#848 add index method to GeometryType

Metadata

Property	Value
Reported by	Andreas Dedner (A.S.Dedner@warwick.ac.uk)
Reported at	Dec 1, 2010 21:12
Type	Discussion
Version	Git (pre2.4) [autotools]
Operating System	Unspecified / All
Last edited by	Christian Engwer (christi@conan.iwr.uni-heidelberg.de)
Last edited at	Mar 20, 2012 18:08
Closed by	Christian Engwer (christi@conan.iwr.uni-heidelberg.de)
Closed at	Mar 20, 2012 18:08
Closed in version	2.2
Resolution	Implemented
Comment	Judging from the comments this feature is implemented to everybodies liking.

Description

Here two suggestions for GeometryType - the first one is the central one:

A) To avoid some of the problems caused by the fact that each Topology is represented by two topologIds (due to the lowest bit) I suggest to add the following to the GeometryType:

size_t index() const { return (topologyId_ >> 1); }
size_t size() const { return (1 << (dim_-1)); } static size_t size(int dim) { return (1 << (dim_-1)); }

This makes it easier to use the topologyId for vector storage because one otherwise has to do the shift oneself or use twice as much storage and then runs into difficulties because each type uses two different sentries in the vector.

Furthermore it simplifies the rest of the GeometryType implementation, e.g.

bool operator==(...) { return other.dim_==dim_ && other.index()==index(); }

B) there are at least 7 ways to construct a 1d line:

1. GeometryType(1) (id=0)
2. GeometryType(1u) (id=0)
3. GeometryType(0,1) (id=0)
4. GeometryType(1,1) (id=1)
5. GeometryType(Simplex) (id=0)
6. GeometryType(Cube) (id=1)
7. makeLine (id=0) Do we need the first two? (3) and (4) seem just as good... They are used in onedgrid but apparently nowhere else in dune-grid at least.

and for consistency makeLine(int id=0) seems to make sense...